That is something a business is supposed to do. Like in an environment when several workhands has to do the job, maybe on a shift....
Me, I standardise everything I do and makes notes of what I do, and never change a winning team.....
Testing was done a looong while ago, to my satisfaction, thank you.
Besides I have proof of what has worked and what not.
From memory : washing for an hour tested out OK, even after just half an hour. I tested that while at school where I had all kinds of esoteric chemicals at my fingertips.
Since I did study chemistry and had to learn these things, chemical analysis among other subjects, where cleanliness and 100% washing are studied in detail, I discovered that running water is a bad way to do things, and wastes lots and lots of water (in the chemical industry, water is an expensive chemical!). WE did a project in school about this, with other chemicals, but still tested this, washing out impurities by running water and change of water. Running water was clearly inferior.
Ilford states the 3 changes is enough. My formal education says its *enough* for quick analysis, but not for archival purposes.
Six changes is of course way, way better, and is more than required, and just for the hull of it, I do seven changes, its fast and easy, takes just a few extra minutes, have done for years and never looked back.
I have a hunch that most tests designed this are just that, TESTS, while proof in the pudding is storing the negativs and prints for 100 years, checking if they survived unscatched!
I also keep the family's negatives, 4x6,5 and 6x9's from well before WW2. Back to the early 1930's for sure, maybe earlier, my fathers brother, my dear uncle was more than 10 years his senior, and started photography early in life.
As an honor to the old guy that developed the negatives (I used to know him), the negatives are still like new.
He would have put up a stoopid face if asked "did you test for retained hypo". But his work and his work ethics was immacculate, and his work survives just fine. He used stand chemivals BTW, deep tanks and Agfa chemistry, replenished both the developers and fixers whenever needed after standard Agfa tests. His prints survives too, even after spending 20 plus years in my wallet, I bet I put in more bad stuff from the walllets leather, tan ever from development!
Sometimes this becomes like the emperors clothes, it is possible to pick every nit in excess, so to speak.
My 50 years of developing negatives speaks well enough for me, and thats it.